Add an addition check for undefined behavior for when we hit a __builtin_unreachable.  WIP.
Add an addition check for undefined behavior for when we hit a
__builtin_unreachable.  WIP.


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@91499 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang